The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Host devices such as computers, laptops, servers, etc., typically store data on storage devices such as hard disk drives. Referring now to FIG. 1, an exemplary hard disk drive 10 is shown to include a hard disk drive (HDD) system 12 and a hard drive assembly (HDA) 13. The HDA 13 includes one or more circular recording surfaces 14. The recording surfaces 14 are coated with magnetic layers 15. Data is recorded on the recording surfaces 14 in the form of digital bits called ones and zeros
A spindle motor, shown schematically at 16, rotates the recording surfaces 14. Generally, the spindle motor 16 rotates the recording surfaces 14 at a fixed speed during read/write operations. One or more read/write actuator arms 18 moves relative to the recording surfaces 14 to read and/or write data to/from the recording surfaces 14.
A read/write device 20 is located near a distal end of the read/write arm 18. The read/write device 20 includes a write element such as an inductor that generates a magnetic field. The read/write device 20 also includes a read element (such as a magneto-resistive (MR) element) that senses the magnetic field on the recording surfaces 14.
A preamp circuit 22 amplifies analog read/write signals. When reading data, the preamp circuit 22 amplifies low level signals from the read element and outputs the amplified signal to a read channel device 24. When writing data, a write current is generated which flows through the write element of the read/write device 20. The write current is switched to produce a magnetic field having a positive or negative polarity. The positive or negative polarity is stored on the recording surfaces 14 and is used to represent data.
The HDD 12 typically includes a buffer 32 that stores data that is associated with the control of the hard disk drive. Additionally, the buffer 32 buffers data that is read or that is to be written. The data thus buffered is then transmitted as data blocks to improve efficiency of reading and writing. The buffer 32 may employ DRAM, SDRAM, or other types of low latency memory. The HDD 12 further includes a processor 34 that performs processing related to the operation of the HDD 10.
The HDD 12 further includes a hard disk controller (HDC) 36 that communicates with a host device via an input/output (I/O) interface 38. The I/O interface 38 can be a serial or parallel interface, such as an Integrated Drive Electronics (IDE), Advanced Technology Attachment (ATA), or serial ATA (SATA) interface. The I/O interface 38 communicates with an I/O interface 44 that is associated with a host device 46.
The HDC 36 also communicates with a spindle/voice coil motor (VCM) driver 40 and/or the read channel device 24. The spindle/VCM driver 40 controls the spindle motor 16 that rotates the recording surfaces 14. The spindle/VCM driver 40 also generates control signals that position the read/write arm 18 using a voice coil actuator, a stepper motor, or any other suitable actuator.
Some electronic devices in the disk drives perform complex functions. For example, the read channel device 24 may incorporate an efficient data-encoding scheme in addition to advanced digital filtering and data-detection techniques. The read channel device 24 may thereby increase areal densities and data transfer rates of disk drives. Thus, testing devices such as the read channel device 24 may ensure data reliability.
Generally, external test equipment is used to test electronic devices such as the read channel device 24. Disk drives, however, are steadily decreasing in size and increasing in speed. This is because use of disk drives is proliferating in small electronic devices such as MP3 players, game consoles, digital cameras, etc. These devices typically use compact disk drives having high storage capacities and high data transfer rates. As a result, physical dimensions of disk drives are steadily shrinking. This makes using external test equipment increasingly impractical. Consequently, conventional test equipment may be unable to test complex devices and subsystems such as read channel devices, hard disk controllers, etc., in compact and high-speed disk drives.